We seek to develop through a revised competing continuation (NR04513) a greater understanding of the effects of nurse staffing and the nurse practice environment on nurse and patient outcomes by exploiting natural experiments that are anticipated to change staffing and practice environments and exploring the effects of those factors over time, and across different states, using multiple methods and measures. We propose to extend our 1999 study of the outcomes of nurse staffing and nurse practice environments in 182 Pennsylvania hospitals at a second point in time (in 2006) and, in that same year, extend our study to include parallel data from roughly 402 hospitals in California, where mandatory nurse staffing ratio legislation has created the largest natural experiment ever in hospital nurse staffing change. We will also, for all hospitals in both states, and for every year from 1998 to 2007, compile hospital-level data on staffing and hospital-level and patient-level data on mortality and other adverse events. The expanded cross-sectional data for 2006 will enable us to resolve many of the questions involving how best to measure and disentangle the potentially interactive effects of nurse staffing (including nurse education) and nurse practice environments on nurse and patient outcomes. The repeated cross-sectional data from Pennsylvania, and the longitudinal data on staffing and patient outcomes from both states, will provide better evidence for establishing the causal relationships between nurse staffing, nurse education, nurse practice environments, and nurse and patient outcomes, since investigating changes in hospitals over time involves using each hospital as its own control. The use of patient outcomes beyond mortality and failure to rescue will allow us to more completely capture the effects of nurses and nursing on the large number of patients who, while not at great risk of dying, are nonetheless vulnerable to a wide range of unfavorable outcomes. This research has the potential to advance the field of nursing outcomes research and to yield critical insights relevant to stemming the flight of nurses from front line care roles and improving hospital outcomes. [unreadable] [unreadable]